- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus
摘要： Two-dimensional (2D) horizontal fields of cloud optical thickness derived from airborne measurements of solar spectral radiance during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign (carried out in Inuvik, Canada in April/May 2012) are compared with semi-idealized Large Eddy Simulations (LES) of Arctic stratus performed with the COnsortium for Small-Scale MOdeling (COSMO) atmospheric model. The input for the LES is obtained from collocated airborne dropsonde observations. Four consecutive days of a persistent Arctic stratus observed above the sea-ice free Beaufort Sea are selected for the comparison. Macrophysical cloud properties such as cloud top altitude and vertical extent are well captured by COSMO. Cloud horizontal inhomogeneity quantified by the standard deviation and one-dimensional (1D) inhomogeneity parameters show that COSMO produces only half of the measured horizontal cloud inhomogeneities, while the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional cloud inhomogeneity structures strongly depend on the mean wind speed. A threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity.
关键词： airborne measurements,COSMO model,horizontal inhomogeneity,wind speed sensitivity,Large Eddy Simulation,Arctic stratus,cloud optical thickness
更新于2025-09-23 15:23:52
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Wind Speed Extrapolation using Machine Learning Methods and LiDAR Measurements
摘要： Accurate wind energy assessments require wind speed (WS) at the hub height. The cost of WS measurements grows enormously with height. This paper utilizes deep neural network (DNN) algorithm for the extrapolation of the WS to higher heights based on measured values at lower heights. LiDAR measurements at lower heights are used for training the system and at higher heights for performance analysis. These measurements are made at 10, 20, . . . , and 120 m heights. First, the measured WS values at 10–40 m were used to extrapolate values up to 120 m. In the second scenario, the WS at 10–50 m were used to extrapolate values up to 120 m. This continued until the last scenario, in which the WS at 10–100 m were used to estimate values at 110 and 120 m. A relationship between heights of measurements and the accuracy of the WS estimation at hub height is presented. The WS extrapolated using the present approach is compared with the measured values and with local wind shear exponent (LWSE)-based extrapolated WS. Furthermore, to analyze the performance of the DNN relative to other machine learning methods, we compared its performance with that of classical feedforward artificial neural networks trained using a genetic algorithm to find the initial weights and the Levemberg–Marquardt (LM) method (GANN) for training. The mean absolute percent error between measured and extrapolated WS at height 120 m based on measurements between 10–50 m using DNN, GANN, and LWSE are 9.65%, 12.77%, and 9.79%, respectively.
关键词： wind speed profile,renewable energy,machine learning,Extrapolation
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - Coastal Ocean Wind Speed Estimation Based GNSS-Reflectometry of BeiDou GEO Satellite
摘要： Global Navigation Satellite System-Reflectometry (GNSS-R) is useful for the ocean remote sensing. It has shown promising results as altimetry, Significant Wave Height, and wind speed measurement. To retrieve the information of the ocean surface, the GNSS-R technique receive the direct signal from GNSS satellites and capture the reflected signal by GNSS-R receivers. The difference delay of the reflected signal provided difference characteristics of the ocean including wind speed information. The aim of this paper is to estimate the ocean wind speed in the coastal area using the reflected signal information. This paper used the observed data sets from 3 to 12 January 2014 collected from the Geostationary Earth Orbit (GEO) of Chinese satellite (BeiDou G1) which consist of phase I and Q component and the in situ wind speed measurement collected from buoy station. A Method based on Artificial Neural Network (ANN) technique for wind speed estimation was presented. In addition, Particle Filter (PF) based autoregressive model was used to improve the efficacy of ANN. The performance of proposed technique has evaluated by using the Root Mean Square Error (RMSE) as shown in the experimental result section.
关键词： Particle Filter,GNSS-Reflectometry,Wind Speed Estimation,ANN,BeiDou GEO satellite
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - The Wind Speed Inversion and In-Orbit Assessment of Imaging Altimeter on Tiangong-2 Space Station
摘要： Imaging ALTimeter (IALT) is a new type of radar altimeter system, which observes the earth from 2° to 7° incident angles. In comparison to the conventional altimeters such as HY-2A altimeter, Jason-1/2, TOPEX/Poseidon, which observe the ocean at nadir, the swath of IALT is much wider and its spatial resolution is much higher. The IALT on board Tiangong-2 space station is launched on 15th September, 2016 at Jiuquan Satellite Launch Center. The in-orbit assessment of IALT is done until 30th April, 2017. In this paper, the ocean surface wind speed inversion method based on IALT is established. The neural network algorithm is used for ocean surface wind speed retrieval, and the spatial resolution of retrieved wind speed is 25km. The wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed, buoy wind speed, and boat measurement wind speed. The results show that the Root-Mean-Square (RMS) of retrieved wind speed is 1.85m/s, and the Bias of retrieved wind speed is about -0.21m/s. The wind speed inversion accuracy satisfies performance requirement.
关键词： in-orbit assessment,Imaging ALTimeter,ocean surface wind speed,inversion accuracy
更新于2025-09-23 15:21:21
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The influence of dust deposition on the temperature of soiling photovoltaic glass under lighting and windy conditions
摘要： Module temperature has significant influence on the energy harvest and energy conversion efficiency of solar cells, which varies greatly with dust deposition and the wind-blowing. In this paper, several sets of experiments were carried out to test the temperature of soiling photovoltaic glass plate under lighting and windy conditions. The results indicate that the temperature of the upper and lower surface is much higher than that of the clean glass plate, and the dust deposition can exert great impact on the temperature of lower surface compared with that on the upper surface. At the same time, under the lighting and windy conditions, the maximum temperature of the photovoltaic glass plate decreases exponentially with increasing wind speed. The final temperature of clean glass plate tends to be consistent with the ambient one, while the temperature of dusty glass plate is much higher than air temperature. Through simulating the external electromagnetic field of spherical particle irradiated by the plane wave, we firstly found that the deposition particles can result in light convergence in its wavefront direction, and the light intensity can also be enhanced, significantly heating the glass plate. All our preliminary results throw light on the effect of dust deposition on the photovoltaic panel temperature in the desert, which can be helpful to establish a more reliable physical model of photovoltaic power generation efficiency involving environmental factors.
关键词： Wind speed,Dust deposition,Photovoltaic glass,Temperature
更新于2025-09-23 15:19:57
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A Turbulence-Oriented Approach to Retrieve Various Atmospheric Parameters Using Advanced Lidar Data Processing Techniques
摘要： The article is aimed at presenting a semi-empirical model coded and computed in the programming language Python, which utilizes data gathered with a standard biaxial elastic lidar platform in order to calculate the altitude profiles of the structure coefficients of the atmospheric refraction index C2N(z) and other associated turbulence parameters. Additionally, the model can be used to calculate the PBL (Planetary Boundary Layer) height, and other parameters typically employed in the field of astronomy. Solving the Fernard–Klett inversion by correlating sun-photometer data obtained through our AERONET site with lidar data, it can yield the atmospheric extinction and backscatter profiles α(z) and β(z), and thus obtain the atmospheric optical depth. Finally, several theoretical notions of interest that utilize the solved parameters are presented, such as approximated relations between C2N(z) and the atmospheric temperature profile T(z), and between the scintillation of backscattered lidar signal and the average wind speed profile U(z). These obtained profiles and parameters also have several environmental applications that are connected directly and indirectly to human health and well-being, ranging from understanding the transport of aerosols in the atmosphere and minimizing the errors in measuring it, to predicting extreme, and potentially-damaging, meteorological events.
关键词： RCS,temperature profile,structure coefficients,environment,human health,atmospheric extinction,atmospheric backscatter,wind speed profile,lidar,turbulence
更新于2025-09-19 17:15:36
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Profiling wind and greenhouse gases by infrared-laser occultation: results from end-to-end simulations in windy air
摘要： The new mission concept of microwave and infrared-laser occultation between low-Earth-orbit satellites (LMIO) is designed to provide accurate and long-term stable profiles of atmospheric thermodynamic variables, greenhouse gases (GHGs), and line-of-sight (l.o.s.) wind speed with focus on the upper troposphere and lower stratosphere (UTLS). While the unique quality of GHG retrievals enabled by LMIO over the UTLS has been recently demonstrated based on end-to-end simulations, the promise of l.o.s. wind retrieval, and of joint GHG and wind retrieval, has not yet been analyzed in any realistic simulation setting. Here we use a newly developed l.o.s. wind retrieval algorithm, which we embedded in an end-to-end simulation framework that also includes the retrieval of thermodynamic variables and GHGs, and analyze the performance of both stand-alone wind retrieval and joint wind and GHG retrieval. The wind algorithm utilizes LMIO laser signals placed on the inflection points at the wings of the highly symmetric C18OO absorption line near 4767 cm?1 and exploits transmission differences from a wind-induced Doppler shift. Based on realistic example cases for a diversity of atmospheric conditions, ranging from tropical to high-latitude winter, we find that the retrieved l.o.s. wind profiles are of high quality over the lower stratosphere under all conditions, i.e., unbiased and accurate to within about 2 m s?1 over about 15 to 35 km. The wind accuracy degrades into the upper troposphere due to the decreasing signal-to-noise ratio of the wind-induced differential transmission signals. The GHG retrieval in windy air is not vulnerable to wind speed uncertainties up to about 10 m s?1 but is found to benefit in the case of higher speeds from the integrated wind retrieval that enables correction of wind-induced Doppler shift of GHG signals. Overall both the l.o.s. wind and GHG retrieval results are strongly encouraging towards further development and implementation of a LMIO mission.
关键词： greenhouse gases,Doppler shift,microwave and infrared-laser occultation,line-of-sight wind speed,upper troposphere and lower stratosphere
更新于2025-09-12 10:27:22
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Search for Best Astronomical Observatory Sites in the MENA Region using Satellite Measurements
摘要： We perform a systematic search for astronomical observatory sites in the MENA (Middle-East and North Africa) region using space-based data for all the relevant factors, i.e. altitude (DEM), cloud fraction (CF), light pollution (NTL), precipitable water vapor (PWV), aerosol optical depth (AOD), relative humidity (RH), wind speed (WS), Richardson Number (RN), and diurnal temperature range (DTR). We look for the best locations overall even where altitudes are low (the threshold that we normally consider being 1,500 m) or where the combination of the afore-mentioned determining factors had previously excluded all locations in a given country. In this aim, we use the rich data that Earth-observing satellites provide, e.g. the Terra and Aqua multi-national NASA research satellites, with their MODIS (Moderate Resolution Imaging Spectroradiometer) and AIRS (Atmospheric Infrared Sounder) instruments, the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS), and other products from climate diagnostics archives (e.g. MERRA). We present preliminary results on the best locations for the region.
关键词： diurnal temperature range,Richardson Number,MENA region,wind speed,precipitable water vapor,cloud fraction,relative humidity,aerosol optical depth,light pollution,astronomical observatory sites,satellite measurements
更新于2025-09-11 14:15:04
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Validating precision estimates in horizontal wind measurements from a Doppler lidar
摘要： Results from a recent field campaign are used to assess the accuracy of wind speed and direction precision estimates produced by a Doppler lidar wind retrieval algorithm. The algorithm, which is based on the traditional velocity-azimuth-display (VAD) technique, estimates the wind speed and direction measurement precision using standard error propagation techniques, assuming the input data (i.e., radial velocities) to be contaminated by random, zero-mean, errors. For this study, the lidar was configured to execute an 8-beam plan-position-indicator (PPI) scan once every 12 min during the 6-week deployment period. Several wind retrieval trials were conducted using different schemes for estimating the precision in the radial velocity measurements. The resulting wind speed and direction precision estimates were compared to differences in wind speed and direction between the VAD algorithm and sonic anemometer measurements taken on a nearby 300 m tower.
关键词： VAD algorithm,precision estimates,wind speed,wind direction,Doppler lidar,sonic anemometer
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A New Azimuth Cut-Off Procedure to Retrieve Significant Wave Height Under High Wind Regimes
摘要： In this study, the azimuth cut-off approach, which is typically adopted to estimate wind speed from Synthetic Aperture Radar (SAR) imagery collected under nominal wind conditions, is discussed with respect to high wind regime cases. First, the key roles played by the pixel spacing, the size of the boxes used to partition the SAR imagery and the image texture (homogeneity) are discussed in terms of their effects on the azimuth cut-off (λc) estimation. Then, the reliability of the λc estimation is analyzed by measuring the distance between the measured and fitted autocorrelation functions (ACFs). This analysis shows that it is of paramount importance to filter unfeasible/unreliable λc values. To identify those values in an objective way a criterion is proposed that is based on the χ2 test performed over a large dataset of Sentinel-1 SAR imagery. The effectiveness of the χ2 test is verified by correlating the accepted estimates against auxiliary significant wave height data.
关键词： SAR,significant wave height,wind speed,azimuth cut-off
更新于2025-09-10 09:29:36